Reheating a Compost Pile

A properly constructed compost pile produces the heat necessary to break down the components, kill weeds and reduce odors. Temperatures up to 145 degrees Fahrenheit are often necessary to kill the seeds of persistent weeds. If the compost pile doesn't heat or cools down before the compost is finished, simple fixes can raise the temperature again.

Construction

A pile that is too small or is poorly constructed won't heat properly. The compost heap should be at least 3 feet tall and 3 feet wide to produce heat. Increase the size of the pile if necessary to achieve the recommended dimensions. If the pile is long, move the materials into a condensed pile. A heap that compacts quickly or slumps may also have structural problems that won't allow the materials to reach the desired temperature. Add more materials to bulk up the pile.

Components

The main components required in a compost pile are carbon, nitrogen, water and oxygen. These elements work together to create the rich compost. If the proportions of those components are off, you may need to make adjustments in order to reheat the pile. Check the moisture level — the pile should be relatively damp. If you can't squeeze any water out of the compost material, add water. But if the ingredients are soggy and saturated, add extra dry materials. A lack of nitrogen can also prevent the pile from heating properly. To reheat the heap, add nitrogen-containing materials like grass clippings and vegetable peels.

Insulation

A layer of insulation helps heat up the contents of the pile. The insulating layer is particularly useful during cooler weather when the outside temperature may affect the temperature of the materials in the pile. A variety of materials work as insulation, including natural materials like straw or soil. You can also use man-made products like plastic sheeting to help the decomposing materials retain heat. When you need to tend to the compost heap, simply lift the insulating layer to reach the materials underneath.

Tips

Turning the pile often helps reheat the materials in the compost heap. When the pile lacks oxygen, you may notice the temperature gradually decrease over the course of a few days. Stirring up the materials helps aerate them so they can reheat. If the pH of the pile is low, you may notice a failure to heat or a garbage smell from the pile. Mixing in wood ash or lime increases the pH to encourage reheating. A compost thermometer helps you monitor the temperature to determine if interventions are needed.